1. Field of the Invention
This invention relates to a lumbar support, and more particularly to an adjustable lumbar support for a backrest.
2. Background Art
In an adjustable lumbar support for a backrest, a cam member is rotated by a lever mounted on the backrest. As a result, a support plate within the backrest is moved in a horizontal direction normal a plane generally defined by the backrest using a torsion member cooperating with the cam member. Horizontal adjustment of the position of the support plate permits regulation of the degree of pressure the support plate exerts on the back of the portion of the backrest designed to be aligned with the lumbar region of a user, thereby reducing back fatigue. Such an adjustable lumbar support for a backrest is disclosed in applicant's U.S. patent application Ser. No. 6/480,574, filed Mar. 30, 1983.
In the lumbar support described above, regulation of the height at which the support plate presses against the back of the backrest is conventionally not available. Nevertheless, there are height differences in the lumbar position of users of such a backrest, according to the physical characteristics of each. Without the capacity to adjust the height of a lumbar support for a backrest, the most appropriate and comfortable lumbar support for each user cannot be obtained.